Integrity Constraints in Spatial Databases

Abstract

This chapter addresses the relationship that exists between the nature of spatial information, spatial relationships, and spatial integrity constraints, and proposes the use of OMT-G (Borges et al., 1999; Borges et al., 2001), an object-oriented data model for geographic applications, at an early stage in the specification of integrity constraints in spatial databases. OMT-G provides appropriate primitives for representing spatial data, supports spatial relationships and allows the specification of spatial integrity rules (topological, semantic and user integrity rules) through its spatial primitives and spatial relationship constructs. Being an object-oriented data model, it also allows some spatial constraints to be encapsulated as methods associated to specific georeferenced classes. Once constraints are explicitly documented in the conceptual modeling phase, and methods to enforce the spatial integrity constraints are defined, the spatial database management system and the application must implement such constraints. This chapter does not cover integrity constraints associated to the representation of simple objects, such as constraints implicit to the geometric description of a polygon. Geometric constraints are related to the implementation, and are covered here in a higher level view, considering only the shape of geographic objects. Consistency rules associated with the representation of spatial objects are discussed in Laurini and Thompson (1992).